Internal combustion engines



July 9, 1957 F. A. .HIERSCH 2,798,361

INTERNAL COMBUSTION ENGINES Original Filed Aug. 19, 1947 5 Sheets-Sheetl S Q E "III/IIIIIIIIIIII/II III/IIIIIIIIIIIIIIIIIIIIIIA! INVEN TOR.

FRtfDER/GK A. HIERSOH ATTORNEYS.

July 9, 1957 F. A. HIERSCH 2,798,361

INTERNAL COMBUSTION ENGINES Original Filed Aug. 19, 1947 3 Sheets-Sheet2 O m l INVENTOR.

FEEDER/0K A. HIERSGH ATTORNEYS July 9, 1 957 F. A. HIERSCH INTERNALCOMBUSTION ENGINES 5 Sheets-Sheet 3 Original Filed Aug. 19, 1947 IN VENTOR. FREDERICK A HIE RSOH A T TORNE Y5.

United States Patent i INTERNAL (IONEUSTION ENGINES Frederick A.Hiersch, Detroit, Mich, assignor to Continental Aviation and EngineeringCorporation, Detroit, Mich, a corporation of Virginia Originalapplication August 19, 1947, Serial No. 769,813. Divided and thisapplication July 6, 1953, Serial No.

2 Claims.- (Cl. oil-35.6)

This invention relates to an internal combustion engine of the ram jettype, and especially to a fuel preheater for such an engine.

For maximum efficiency, a power plant should be designed to minimizeheat losses. Heat exchangers are a common expedient to that end. It isdesirable that aircraft be made as light as possible without sacrificingstrength.

It is an object of this invention to provide a ram jet engine in which aheat exchanger is so located as to minimize heat losses. In someembodiments of the invention, the heat exchanger is so designed as toadd to the structural strength and rigidity of the engine housing.

In the drawings:

Fig. 1 is a longitudinal sectional view through a jet engine embodyingthe invention.

Fig. 2 shows the helically wound storage tank of the engine of Fig. 1,but in Fig. 2 the storage tank is shown as a straight tube, for thepurposes of explaining its function.

Fig. 3 shows another embodiment of the invention, being a developed Viewof another form of heat exchanger.

Fig. 4 is a view in section on line 4-4 of Fig. 3.

' Fig. 5 is an enlarged detail view of the embodiment shown in Fig. 3,illustrating a modification of this embodiment.

Fig. 6 is a view in section substantially on line 66 of Fig. 5.

Fig. 7 is a view in section substantially on line 7--7 of Fig. 5.

Fig. 8 is a perspective view showing still another embodiment of a heatexchanger made according to the invention.

Fig. 9 is a view in section substantially on line 99 of Fig. 8.

Fig. 10 is a developed view, with the outer wall removed, of the heatexchanger shown in Fig. 8, and

Fig. 11 is a view in section on line 11-11 of Fig. 10.

This is a divisional case of my copending application Serial No.769,813, filed August 19, 1947, for Internal Combustion Engine, nowabandoned.

Fig. 1 shows a ram jet engine made according to the invention,substantially in its entirety. As can readily be seen from Fig. 1, theengine comprises a multiple walled housing 2. In the forward end of thehousing 2 there is a difiuser section 4 formed by the inside of housing2 and inner body 6. Approximately amidships there is a combustionchamber section 8 which extends rearward to a point near the nozzle 10at the end of the housing.

The nozzle 10 at the tail end of the engine is fitted with a plug 12which is movable axially of the housing to vary the nozzle diameter.Plug 12 consists of a hollow bulbous body 14. A cavity 16 is formed bythe wall of body 14 and an end cap 18. The body 14 is preferably made ofa porous metal such as porous chrome metal made by the baking sodaprocess having wide use for seat cooling and which permits a known rateof gas ice leakage therethrough. The plug 12 is hydrogen cooled,hydrogen being admitted through the passage 20 from a hydrogen tank 22located in the inner body 6. Suitable control means 24 are alsopreferably located in the inner body 6, and serve to control thefunctioning of the jet engine.

The forward end of the engine houses a fuel tank 26 which is preferablyhelically wound into a coil located between the two walls of themultiple walled housing. This housing consists of an outer Wall 28 andan inner wall 30. In the preferred form, the fuel tank 26 is maintainedunder pressure, hydrogen from the tank 22 being utilized for thispurpose. As can best be seen in Fig. 2, the fuel tank is provided with atake off tube 32 which communicates with a tube 34 which issubstantially coextensive with the fuel storage tank. Tube 34 isprovided with valves 36 at numerous stations throughout its length. InFig. 2, valves 36 are shown only at the extreme ends of the tube 34, butit will be understood by those skilled in the art that other valves maybe disposed at one or more stations between the ends.

Valves 36 are shown only diagrammatically in Fig. 2, inasmuch as they donotthemselves constitute the invention in this case. Valves 36 may beany suitable valve which is sensitiveto the presence of liquid, as forexample, a solenoid operated valve which is electrically actuated to beopen when the valve is surrounded by vapor. Numerous valves suitable forthis purpose are available, and the details thereof need not be setforth here. The object of the tube 34 is to permit liquid to be drawnoff through the outlet 32 at all times, regardless of the location ofliquid in the tank.

Liquid which is withdrawn from the fuel tank through the outlet 32 isdelivered to an annular header 38 which is located amidships adjacentthe fuel storage tanks. Tubes 40 communicate at one end with header 38.These tubes 40 extend rearward from header 38 in a helix which is woundin the right hand direction to a point or plane 42 near the tail of theengine. From this point, the tubes bend forward and wind in a left handhelix toward the header 44, to which they return the fuel. Fuel passesfrom header 44 to nozzles, not shown, which feed the fuel to thecombustion chamber.

Thus we have the tube halves 46 forming a right hand helix, and the tubehalves 48 forming a left hand helix. The right hand helix overlies theleft hand helix, and both halves lie in the annular space formed by theinner and outer walls 28 and 30 respectively of the multiple walledhousing. It will be further noted by those skilled in the art that bothhalves of the tube 40 lie in the annular space of that. portion of thehousing which envelopes the combustion chamber 8.

The individual tube type heat exchanger shown in the embodiment of Fig.1 will be found preferably where high pressures are used in thesystem-pressures where the order of magnitude is 1200 p. s. i. Wherelower pressures are used, a preferred type of heat exchanger is onewhich is made so that the fuel conduits add to the structural strengthand rigidity of the housing. Two embodiments of heat exchangers made inthis manner are shown in Figs. 3-11 inclusive.

In Figs. 3-7 inclusive there is shown one embodiment of this type ofheat exchanger. Considering now Figs. 3 and 4, the inner wall 30 and theouter wall 28 of the multiple walled housing are much the same as in thefirst embodiment. In addition there is an intermediate wall 50 disposedbetween walls 28 and 30. The beads 52 form concave grooves which, inconjunction with the inner wall 30, provide flow passages for liquidfuel. The intermediate Wall 50 is preferably seam welded to the innerwall 30 as shown at 53. As will be understood by those skilled 3 in theart, walls 30 and 50 will be seam welded between adjacent beads 52.

The embodiment shown in Fig. 3 may be modified as shown in Figs.5-7:bythe addition of bridges 54 whereit is,desired to substantiallyeliminatethe mixing ofliquid of intersecting beads orpassag'es 52; Eachbridge 54 comprises end portions .adapted to substantially fill the fuelflow passages, and a reduced diameter intermediate portion which isadapted to cross an intersecting fuel passage to permit the passage offuel in one direction through the reduced diameter portion, and in theother direction around the reduced diameter portion. T

It will be understood by those skilled .in the artthat Figs. 3-7inclusive are developed views, and that the 9 actual embodiment of theheat exchanger is cylindrical rather than plane.

' Referring now in detail to Figs. 8-11 inclusive, the outer and innerwalls 28 and 30 are shown much the same as before, with an intermediatewall 56 between walls 28 and 30 and spaced from both of them.Intermediate wall 56 is turned inwardly at both ends and is secured asby welding to inner wall 38 as shown at 58. Intermediate wall 56 isdimpled inward as shown at 60 to space it from the inner wall 30.Intermediate wall 56 is furthermore beaded in a zigzag pattern, thebeads being deformed outwardly as shown at 62, and contacting the outerwall 28. Between the Vs of the zigzag beads, intermediate wall 56 isslotted to form fuel passages '64. A fuel inlet 66 communicates with oneend of the heat exchanger, and a fuel outlet 68 communicates with theother end of the heat exchanger by means of a duct 70 which is providedbetween walls 30 and 56. See especially Figs. and 11.

Operation Referring now to the'embodiment shown-in Fig. 1, fuel isadmitted to header 38, whence it flows through the right hand helix half46 of tubes 40 rearward, returning through the left hand helix 48 to theheader 44. As fuel flows through the tubes 40 it is heated up by theheat escaping from the combustion chamber. The heat exchanger thusserves the purpose of cooling the walls of the combustion chamber, atthe same time that it absorbs heat which might otherwise be lost andturns the heat into useful heat by preheating the fuel before it reachesthe nozzles.

In the embodiment shown in Figs. 37 inclusive, fuel flows through thepassages provided by beads 52, accomplishing the same objects as setforth above in connection with Fig. 1. Where the system is provided withbridges as shown in Figs. 5, 6 and 7, fuel flows inone direction throughthe right hand wound fuel passages, and flows in the other directionthrough the left hand wound passages. The bridges 54 need not beabsolutely fluid type, inasmuch as liquid fuel is present in bothpassages.

In the embodiment shown in Figs. 8-11 inclusive, fuel flows into theheat exchanger by way of inlet 66'flowing to the right as seen in Fig.10, between the converging beads 62, whence it flows radially throughpassages 64 into the space between walls 30 and 56. From this space itflows radially outward again through other passages 64 into the spacebetween beads 62 which diverge toward the right as seen in Fig. 10, andleaves the heat exchanger by way of duct and outlet 68.

It will be understood that the heat exchanger embodiment shown in Figs.3-11 inclusive presents a stronger and more rigid engine housing thanthe tube type shown in Fig. 1. To the end that the tube typeheatexchanger of Fig. 1 may be made more rigid, the heat exchanger may ifdesired be provided with a header or a pair of headers at the rearmostend 42. This modification is not shown, but will be readily understoodby those skilled in the art.

I claim:

1. In a jet engine, a double-walled housing comprising concentricelongated tubular sections disposed in spaced relation to define anannular space, a pair of concentric outer and inner annular headers insaid annular space at the mid-section of said engine arranged incontacting supporting relation with said concentric elongated tubularsections, a combustion chamber within the housing and disposed withinthe rear portion of the engine rearwardly of said headers, a coiled fuelstorage tank ahead of said headers and disposed in said annular space incontacting relation with said tubular sections to support same one fromthe other, an intermediate tubular section fitted into said annularspace enveloping the combustion chamber and providing a rigid supportfor said outer and inner tubular sections, said intermediatetubularsection provided with intersecting channels through which fuelmay be circulated in heat exchange relation with said combustion chamberand connected respectively with the outer and inner headers to receivefuel from said outer header and to discharge the preheated fuel to saidinner header, and means discharging said preheated fuel from said innerheader to said combustion chamber.

2. ha jet engine, a double-walled housing structure comprisingconcentric elongated tubular sections disposed in spaced relation todefine an annular space, a pair of concentric outer and inner annularheaders in'said annular space at substantially the mid section of saidengine, a combustion chamber within the housing and disposed within therear portion of said engine, a fuel storage tank between the two housingwalls in the forward portion of the engine and connected with said outerheader, and a fuel preheater between the two housing walls andencompassing the said combustion chamber, said preheater comprising afabricated structure contacting both said concentric tubular sectionsand providing intersecting conduit portions extending longitudinally ofsaid housing structure communicating in series with said outer end innerheaders, and tubular bridge structure at said intersection of saidconduit portions to provide cross-over passage for said fuel flow andmeans discharging said preheated fuel from said inner header to saidcombustion chamber.

. References Cited in the file of this patent UNITED STATES PATENTS1,601,637 Meigs Sept. 28, 1926 2,338,090 Bradfield Ian. 4, 19442,438,247 Knudsen Mar. 23, 1948 2,469,828 Johnson May 10, 1949 2,540,594Price Feb. 6, 1951

